For galvanically separated power supply, transformers or energy transmitters having a primary coil and a secondary coil which form an isolating distance are frequently used. In EP 1 885 085 A1 there are, separated from one another, an energy transmission interface and a data transmission interface for contactless connection of a bus subscriber. Two secondary windings and two processing units per bus subscriber are not provided.
Also, interfaces are known via which, in addition to energy, signals or data can also be transmitted bidirectionally. In WO 98/15069 A1, a ferromagnetic core limb provided with a primary coil for energy transmission and with a primary coil for data transmission in interaction with a ferromagnetic core limb provided with a secondary coil for energy input and a secondary coil for data acquisition is used. While there is a potential separation with good electrical insulation between the primary side and the secondary side, such a potential separation with good electrical insulation does not exist between the energy side and the data side. Because of the ferromagnetic limbs, relatively free positioning between primary and secondary sides is not possible.
From WO 2010/125048 A1, a system for contactless data and energy supply from a mounting base to bus subscriber modules is known, wherein a supply rail with energy transmission interfaces and data transmission interfaces is provided, and the bus subscriber modules each have a corresponding energy transmission interface and a corresponding data transmission interface. In the case of inductive energy and data transmission, the interface comprises a primary coil with a coil axis perpendicular to the supply rail, and for each bus subscriber module it comprises in each case one secondary-side coil with a coil axis likewise perpendicular to the supply rail.
In WO 2008/118178 A1, the wireless energy transmission is operated by means of resonant fields over a certain distance. This results in potential separation between an electrical energy supply unit and an energy consumer unit, but not in a separation between three potential groups.
From EP 2 067 148 B1, a charging device for a plurality of electronic devices is known, wherein the primary winding comprises a plurality of overlapping coil elements at a contact surface, and the secondary windings receive electromagnetic energy upon positioning on the contact surface. The primary winding is arranged as part of a resonant circuit and includes a capacitor for adapting the resonance frequency of the resonant circuit to the operating frequency. The electronic devices to be charged have no signal-data coupling section between adjacent electronic devices.